1. Field of Use
The present invention relates to a system for diagnosing failures within a peripheral system and more particularly to a system for diagnosing possible sources of future failures in advance of the currents.
2. Prior Art
There are known systems which provide for automatically monitoring the operation of a machine to diagnose degradation of machine operations anticipatory to failure and for determining potential trouble souces of predicted failures. An example of such a system may be found in U.S. Pat. No. 3,787,670 invented by Paul E. Nelson et al., assigned to the assignee of the present invention. While the system disclosed in the patent provides for anticipatory diagnoses of failures, the system is required to perform such operations under the supervision of a central processing unit of the system in accordance with a particular program. A disadvantage of this type of arrangement is that the system resouces such as a central processing unit and associated input/output facilities must be dedicated to the supervision of the diagnostic tests and required to be operating properly before such testing can proceed.
Other prior art systems provide for multi-channel error detection and correction diagnostic operations by utilizing patterns recorded on the magnetic media under the control of a peripheral controller. In this type of system, error patterns are recorded on the recording medium by placing the controller in a diagnostic mode. The patterns recorded are generated by the programmer using a controlling diagnostic program. After such recording, the patterns are read back during a normal mode of operation and the recovery apparatus corrects the error patterns verifying the operation of the readback circuits included within the recovery apparatus. The first disadvantage of this arrangement is that it must rely on the accuracy of the initial writing operation. That is, in creating a bit pattern on tape the occurrence of a write error could result in incorrect diagnosis of the recovery apparatus. Another disadvantage is that this type of check cannot accurately check the performance of the analog circuits (i.e. clock circuits) normally included in the data recovery apparatus.
Accordingly, it is a primary object of the present invention to provide apparatus for directly checking the operation of a peripheral controller.
It is another object of the present invention to provide for checking the operation of a peripheral controller independently of the information contained on the record medium of the devices controlled by the controller.
It is still a further object of the present invention to provide apparatus for checking the performance of recovery circuits included within a peripheral controller.